Java by API/java.awt.event/MouseWheelListener

implements MouseWheelListener

   <source lang="java">

import java.awt.Graphics; import java.awt.event.MouseWheelEvent; import java.awt.event.MouseWheelListener; import java.awt.image.BufferedImage; import java.io.File; import javax.imageio.ImageIO; import javax.swing.JFrame; public class Main extends JFrame {

 private BufferedImage bi;
 private int zoom = 0;
 private static final double ZOOM_AMOUNT = 1.1;
 public static void main(String[] args) {
     new Main("your.jpg").setVisible(true);
 }
 private void sizeToZoom() {
   double factor = Math.pow(ZOOM_AMOUNT, zoom);
   setSize((int) (bi.getWidth() * factor), (int) (bi.getHeight() * factor));
 }
 public Main(String filename) {
   setDefaultCloseOperation(EXIT_ON_CLOSE);
   try {
     bi = ImageIO.read(new File(filename));
   } catch (Exception e) {
     e.printStackTrace();
   }
   sizeToZoom();
   addMouseWheelListener(new MouseWheelListener() {
     public void mouseWheelMoved(MouseWheelEvent e) {
       int steps = e.getWheelRotation();
       zoom += steps;
       sizeToZoom();
     }
   });
 }
 public void paint(Graphics g) {
   g.drawImage(bi, 0, 0, getWidth(), getHeight(), this);
 }

}

 </source>